GATE Overflow | Compiler Design | Test 1 | Parsing | Question: 1

Question

If we merge states in LR(1) parser to form a LALR(1) parser, we may introduce

• A. shift-reduce conflict
  
• B. reduce-reduce conflict
  
• C. no extra conflict
  
• D. both shift-reduce as well as reduce-reduce

Comments

B. we can only introduce R-R conflicts.

Answer 1

ans is B.

It is because we construct LALR parsing table by merging states of CLR(1) which are only separated by look a heads. In doing so we may merge states which introduce R-R conflicts

Answer 2

To go from CLR(1) parsing table to LALR(1) parsing table, we merge the states that have the same final items but different lookaheads.

In doing so, we can only introduce RR conflicts.